USE OF DEMOLISHED CONCRETE AND BRICK AGGREGATES AS ALTERNATIVE MATERIALS IN VARIOUS PAVEMENT LAYERS

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1 USE OF DEMOLISHED CONCRETE AND BRICK AGGREGATES AS ALTERNATIVE MATERIALS IN VARIOUS PAVEMENT LAYERS RAMU K 1*, SREEKAR CHAND K 2* 1. II. M.Tech, Dept of CIVIL, AM Reddy Memorial College of Engineering & Technology, Petlurivaripalem. 2. Asst. Prof, Dept. of CIVIL, AM Reddy Memorial College of Engineering & Technology, Petlurivaripalem. ABSTRACT: While use of alternative materials in roadway construction is increasing day by day, many agencies are still reluctant to consider alternative materials as a suitable substitute for materials already being used. This is mainly due to unfamiliarity with the engineering properties of alternative materials and a lack of suitable sources that supply recycled materials. This report will explain the several properties of alternative materials through laboratory testing. Laboratory tests include basic tests on aggregates, Marshall mix design, indirect tensile strength test, Atterberg s limits, compaction test and California Bearing Ratio (CBR) test. Specifically, this report will investigate the strength and moisture-density characteristics of various alternative materials blended with natural aggregates for use as road construction materials. A feasibility study has been conducted to investigate the possibility of using demolished concrete aggregates and crushed clay brick as aggregates in base and sub base layers respectively. The results showed that the use of demolished concrete aggregates satisfy the basic requirements of base course layer, up to 75 % replacement with virgin aggregates. On the other hand, crushed clay brick aggregates increased the optimum moisture content and decreased the maximum dry density of the sub-base materials compared to those of natural sub base materials. Moreover, the replacement of crushed clay brick increases the optimum moisture content and decreased the maximum dry density. This was mainly attributed to the lower particle density and higher water absorption of crushed clay brick aggregates. The CBR values increases with the replacement level of crushed clay brick aggregates increases. 1. INTRODUCTION 1.1 GENERAL: Large scale infrastructure road development is being carried out in our country. Due to these developments, natural construction materials like soil, aggregates etc. are getting depleted, forcing the authorities to search for alternative road construction materials. In India there is a pressure to increase the use of option materials in road construction. This reduces the amount of natural aggregates that have to be used and enables the alternative materials to be used constructively instead of being sent to landfill. Civilization also produces waste products. Disposal issue of the waste products is a challenging task. Some of these materials are not biodegradable and often leads to environmental pollution. It is estimated that the construction industry in India generates about 10 to 12 million tons of waste annually as per 2001 statistics. While retrievable items such as bricks, wood, metal, titles are recycled, the concrete and masonry waste, accounting for more than 50% of the waste from construction and demolition activities, are not being currently recycled in India. Recycling of concrete and masonry waste is, however, being done abroad in countries like U.K., USA, France, Denmark, Germany and Japan. Concrete and masonry waste can be recycled by sorting, crushing and sieving into recycled aggregate. This recycled aggregate can be used to make concrete for road construction and building material. The quantity of waste materials is generated from construction activity in India is given in table 1.1. Table 1.1 Quantities of waste generation in India (2001)

2 1.2 SOURCES AND USES Constituents Soil, sand, and gravel Bricks and masonry Quantity generated (million tons/year) 4.20 to to 4.40 Concrete 2.40 to 3.67 Metals 0.60 to 0.73 Bitumen 0.25 to 0.30 Wood 0.25 to 0.30 Others 0.10 to 0.15 The main origins of demolished materials are given as follows, i. Construction debris ii. Bridges iii. Fly over iv. Building roads v. Remodeling The following are the uses of demolished materials in road construction: i. Aggregate in bituminous mixtures ii. Granular base and sub-base courses iii. Embankment or filling. iv. Manufacture of concrete and concrete products like bricks. v. Shoulder construction 1.3 ENVIRONMENTAL BENEFITS The following are the environmental benefits from building demolition waste (demolished concrete aggregate, demolished brick aggregate). i. Reduced land disposal and dumping: The use of recycled concrete pavements eliminates the development of waste stockpiles of concrete. Also, as recycled material can be used within the same suburban area, this can lead to a decrease in energy consumption and can help improve air quality through reduced mobile source emissions. ii. Reconstruction of urban streets and expressways results in an enormous waste concrete, creating a massive disposal problem. Recycling can eliminate many of these issues. iii. The demand for disposal space for concrete debris is high in and the recycling plants are reaching their stock capacity and the disposal costs are increasing. This demand is considerably diminished when RCA has an engineered use in projects. 1.4 OBJECTIVES AND SCOPE OF THE PRESENT STUDY The main objectives this work are listed as follows: i. To determine optimum proportion of demolished concrete aggregate replacing virgin aggregates to be used in binder course layers. ii. To determine optimum proportion of demolished brick aggregate to be used in granular sub-base layer. The experimental investigation considered the demolished aggregate obtained from a single source. The use of DCA and DBA are limited to binder course and granular sub-base layers respectively. 2. REVIEW OF LITERATURE Aljassar et al. (2004) evaluated the feasibility of building demolition concrete aggregates in pavement layers. Building demolition waste constitutes a major component of municipal solid waste in Kuwait. Over 90% of this waste is currently land filled, causing extreme pressure on the available landfills sites. At the same time, the sources of natural aggregates are almost depleted, and there is an increasing demand because of the increased construction and maintenance activities. They observed that a large number of concrete buildings in Kuwait are being demolished. Most of the demolition debris is currently disposed of in landfill sites. These sites have limited capacities and are required for other competing types of wastes which cannot be recycled. Moreover, sources of natural aggregates are becoming depleted in Kuwait, and hence aggregates

3 are imported at higher costs. Recycling the building demolition waste can provide a timely opportunity to reduce the problems of disposing off the demolition waste and the aggregate scarcity. They evaluated the use of aggregates obtained from building demolition waste in a local mix of asphalt concrete. They conducted a detailed laboratory study, which included Marshall method of mix design, immersion compression ratio test, loss of stability test and wheel track test. The results obtained from their study showed that the asphalt concrete mix produced using aggregates from demolition waste can meet the requirements of specifications for flexible pavement. Almutairi et al. (2005) reported that, there is an increasing pressure on the construction industry to reduce the cost and improve the quality of our environment. The fact is that both of these goals can be achieved at the same time. Although construction and demolition (C&D) constitutes a major source of waste in terms of volume and weight, its management and recycling efforts have not yet seen in Kuwait. In this regard they focused on recycling efforts leading to the minimization of the total C&D waste that is currently landfilled in Kuwait. They identified the potential problems to the environment, people and economy. Then, they investigated alternative solutions to manage and control this major type of waste in an economically efficient and environmentally safe manner. Blankenagel (2005) conducted a detailed study on the use of recycled concrete material (RCM) as pavement base material. The author evaluated the physical properties, strength properties and durability characteristics of both demolition and haul-back sources of RCM for use as a pavement base material. The study included extensive laboratory and field testing. Laboratory tests included California bearing ratio (CBR), unconfined compressive strength (UCS), stiffness, freeze-thaw cycling, moisture susceptibility, abrasion, and salinity and alkalinity evaluations. The testing included a dynamic cone penetrometer, ground-penetrating radar, a heavy Clegg impact soil tester, a soil stiffness gauge, and a portable fallingweight deflectometer. The laboratory testing indicated that the demolition material exhibited lower strength and stiffness than the haulback material and reduced UCS loss after freeze-thaw cycling. However, the demolition material received a moisture susceptibility rating of good in the tube suction test, while the haul-back material was rated as marginal. Both materials exhibited self-cementing effects that led to approximately 180 percent increases in UCS over a 7-day curing period. Seven-day UCS values were 1260 kpa and 1820 kpa for the demolition and haul-back materials, respectively, and corresponding CBR values were 22 and 55 %. The field monitoring demonstrated that the RCM base layer was susceptible to stiffness changes primarily due to changes in moisture. In its saturated state during spring testing, the site experienced CBR and stiffness losses of up to 60 percent compared to summer time values. Carl Reller (2006) studied on the best practice guidelines for the use of alternative materials and associated processes in road construction. The author mainly focused on runoff or leachate water that has been in contact with alternative materials is not able to discharge to ground water or adjacent water courses. Discharges to the atmosphere are also important but are not the main focus of the guidelines. The author selected the most alternative materials, this means that appropriate processing, stockpiling and transportation procedures must be observed, and in general, the materials should be located above the water table. Encapsulation and sealing of the materials is also desirable, as is provision of appropriate drainage systems. For most alternative construction processes, the main focus is on establishment of appropriate plans and contingency measures to divert water around the site and to contain any water that is collected on the site as a result of heavy rain or a construction mishap such as rupturing a water main. Adequate monitoring carried out to ensure that the water collected at the site is fit for discharge either during the construction operation, or at a suitable juncture following an emergency situation. If discharge is not appropriate the collected water should be removed by vacuum equipment and disposed of appropriately. It is important to recognize that sound environmental management is required for construction activities in general, not only for those involving alternative materials or processes. In many instances the environmental credentials of traditional materials

4 may be more questionable than those of alternative materials, especially considering that a major source of contaminants is deposition by vehicles, a process that occurs irrespective of the composition of the pavement surface. Csiro (2004) reported that class 1 RCA, which is a well graded, good quality RCA with no greater than 0.5% brick content, had the potential for use in a wide range of applications, subject to appropriate test or performance requirements. Applications include partial replacement (up to 30% of coarse RCA) for virgin material in concrete production for non-structural work such as kerbs and gutters. Current field experience with the use of recycled concrete aggregates for structural applications is scarce. It was suggested that Class 1 RCA could be incorporated into 30 to 40 MPa concrete exposed to benign environments but with some penalties in mix adjustment, permeability and shrinkage properties. There were no visual detrimental effects in the concrete and it was expected that the cost of the increase in cement content could be offset by the lower cost of recycled concrete aggregates. RCA has a lower specific gravity ( ) and higher water absorption ( ) than most natural aggregates. Fine RCA, in particular, has an even lower SG of around 2.32 and very high water absorption of 6.2 %. RCA concrete has unit weight in the range of kg/m. It has higher water demand and gave lower compressive strength than control concrete made from natural aggregate at equal water to cement ratio RCA concrete has similar flexural strength but lower elastic modulus than control. RCA also resulted in higher drying shrinkage and creep but comparable expansion to control. The adherence of mortar to the surface of RCA was the main cause of higher water absorption, lower specific gravity and poor mechanical properties. Excessive expansion or swelling can be caused by contamination by plaster and gypsum. Adjustments of the mix design would be necessary to offset the effect of RCA on workability, absorption, strength and shrinkage. In terms of durability properties, RCA concrete has higher rapid chloride ion permeability but similar carbonation rate accelerated carbonation in 4 % CO2 at 50 % RH to control concrete. 3. MATERIAL AND METHODOLOGY 3.1 Methodology: Material selection Laboratory tests o For DCA Basic desirable properties Marshall stability test Indirect tensile strength test Index retained strength test o For BA Basic tests Compaction test CBR test 3.2 Marshall Mix Design Asphalt mixes are used in the surface coarse of road and airfield pavement, some type of asphalt mixes are also used in base and/or binder course of flexible pavements. The desriable asphalt mix properties include (i) stability (ii) density (iii) durability (iv) flexibility (v) resistance to skidding and (vi) workability during contruction. Stability is defined as resisitance of the paving mix to deformation under load is thus a stress level which causes strain depending upon anticipated field condition. Density is directly realted to voids in the compacted mixtures. Stability and density in general are related terms. Durabillity is defined as the resistance of the mix against weathering which causes hardenging and this depends upon loss of volatiles and oxidation. 4. RESULTS AND DISCUSSION 4.1 Aggregate Gradation The demolished aggregates used in this study were broken and graded in such a manner as to follow the mid values of blended DBM grading-ii curve as shown in figure 4.1.

5 Fig. 4.1 Blended gradation curve for DBM grading-ii as per MORTH Table 4.1 Marshall Test results using virgin aggregates. Fig.4.4 Variation of air voids with DCA replacement Table 4.2 Tensile Strength Values For Demolished Concrete Aggregates Replacements. Fig.4.2 Variation of stability with DCA replacement Fig.4.5 Variation of indirect tensile strength value with DCA replacement Fig. 4.3 Variation flow with DCA replacement

6 Fig. 4.6 Variation of retained tensile strength value with DCA replacement Table 4.3 OMC and MDD values variation with BA replacement. Fig. 4.7 Variation of optimum moisture content with crushed brick aggregates. Fig. 4.8 Variation of maximum dry density with crushed brick aggregates. Fig. 4.9 CBR values (unsoaked and 4-day soaked) for each subbase material CONCLUSION The following are the conclusions drawn from this study: The observed physical properties of blended DCA with original aggregates upto 75% replacement of DCA can be suitable for base coarse construction. From the stability point of view all the replacements of DCA were within the specified value, it means all combinations can satisfied the basic requirement. Based on the flow value upto 75% DCA can be suitable for base coarse construction. From the air voids in total mix results one can conclude that all the replacements are suitable for base coarse preparation. Voids filled with bitumen results proved that up to 50% replacement can satisfy the basic requirements of base coarse. A decreasing trend was observed in density values as DCA replacement increased. Decreasing trend was observed from indirect tensile strength test values and the same trend was recorded in retained tensile strength values. This shows that upto 50% DCA replacement will give satisfactory results. Crushed clay brick had the highest water absorption value, followed by demolished concrete aggregate and natural aggregate. Natural aggregate had the highest density, followed by demolished concrete aggregate and crushed clay brick aggregates. As the coarse crushed clay brick content increases the maximum dry density decreases and the optimum moisture content increase. The increasing trend was observed with the increase in replacement of coarse crushed clay brick content. Replacement rate upto 20% of crushed clay brick aggregates is suitable for low trafficked rural roads and from 40% to 100% of crushed clay brick aggregates replacement are suitable for traffic upto 2 msa. Replacement rates from 80% to 100% of crushed clay brick aggregates can satisfy the requirements of road traffic exceeding 2 msa.

7 REFERENCE 1. Ahmad H. Aljassar., Khalifa Bader Al-Fadala. and Mohammed A. Ali. (2005) Recycling building demolition waste in hot-mix asphalt concrete. Journal of materials in civil engineering, Civil Engineering Department, Kuwait University, Safat, Kuwait. 2. Athar Saeed, P.E. (2006) Evaluation, design and construction techniques for airfield concrete pavement used as recycled material for base. An innovative pavement research foundation research report, Applied research associates, Inc, Ireland. 3. Brandon James Blankenagel. (2005) Characterization of recycled concrete for use as Pavement base material. Research Report, Brigham Young University. 4. Carl Reller. (2006) Best practice guidelines for the use of alternative materials and processes in road construction with respect to environmental issues. 5. Crabb, G. and Raid, M. (2003), Protocols for alternative materials in construction. Produced ByViridis.[ cols/protocols Alternative Materials.Pdf] 6. Nataatmadja and Y. Tan. (1996) Characterisation of recycled crushed concrete aggregates for road base. Technical Paper, School of Engineering, Griffith University, Queensland, Australia. 7. Nataatmadja, Andreas. and Tan, Y.L. (2001) Resilient response of recycled concrete 8. road aggregates. Journal of Transportation Engineering 127(5):pp Nancey Green Leigh. and Lynn M. Patterson. (2004) Construction & demolition debris recycling for environmental protection and economic development. Practice Guide-7, Southeast Regional Environmental Finance Centre, University Of Louisville. 10. SR Elias Ozkan. and A. Duzgunes. (2000) Recycling of construction material and the reuse of building components. A Case Study in Turkey, Department Of Architecture, Middle East Technical University, Turkey. 11. Stephen D. Cosper. (2004) Reuse of concrete materials from building demolition. Technical Bulletin, Department of the Army U.S. Army Corps of Engineers, Washington,